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^stata of
Lean iuneritua
■ E.. Coo ley
If
E
With Special Reference to
THE BLEICHERT PATENT SYSTEM
ALSO
Single Moving-Rope Tramways,
Quarry Cable Hoists
AND
Transmission of Power,
BY
E. GYBBON SPILSBURY.
THE TRENTON IRON CO.,
TRENTON, N. J.
COOPER, HEWITT & CO., 17 Burling Slip,
NEW YORK.
1890.
ill
/"^
N.
Wire Rope Tramways.
Wire Rope Tramways, as a means of cheap transportation, are
> too well known already to require any long dissertation on their
advantages. As feeders to established systems of railroad or water
^ communication, their low cost of construction through countries
^ where, from the rugged contour of the surface, ordinary railroad, or
even wagon-road building would be scarcely practicable, except with
long and costly detours, has always made them very attractive to the
miner and quarryman, to whose use in this country they have been
heretofore almost exclusively confined. The earliest tramways of
this kind which were successfully introduced consisted of a single,
moving, endless rope, from which the loads were suspended. In the
system of Hodgson the buckets or carriers are attached to saddles
which ride on the rope, but can be separated from it. In the modifi-
cation of Hallidie, the carriers are attached permanently to the rope.
But in each of these systems one and the same rope both supports
and moves the load.
This fact is really the reason that aerial transportation has
hitherto not become general in the United States. Lines constructed
with the single moving rope, while very efficient for certain purposes,
are not available for general use as a means of transportation, because
of their limited capacity for carrying individual loads, which in no
case can exceed 300 pounds, and in practice have been much smaller.
The original Hodgson patent tramway and its modification by Hallidie
are the ones chiefly used hitherto in this country. In Europe, how-
ever, while these " single " rope lines were also first in vogue, the
" double " rope system has of late years almost entirely supplanted
them, and has established itself, as a general means of transportation,
to an extent we have hardly yet dreamt of.
4 WIKE KOPE TRAMWAYS.
Railroad companies have adopted these lines as regular feeders
to their main roads, and laws have been promulgated in different
European countries regulating their construction and traffic, the
same as for ordinary railroads. This extension of their application
is due principally, if not entirely, to the perfection attained under the
Bleichert system. The chief advantages this system presents over all
others are as follows :
I St. — While the individual loads to be carried either by the
Hodgson or Hallidie lines should, for convenience and economy,
preferably not exceed 150 pounds, and are, in fact, seldom over 100
pounds, the lines of the Bleichert system are adaptable to individual
loads up to 1,000 pounds each, and in special cases even heavier loads
have been carried.
2d. — All single rope systems of tramways, where the moving
rope carries the load, must necessarily move slowly, otherwise there
is great danger that the rope may jump out of the carrying sheaves.
These carrying sheaves are very shallow, so as to permit the passage
over them of the saddle or clip. The dropping of the rope from the
supporting sheaves has always been a source of more or less trouble
and expense in operating these lines. In the Bleichert system this
trouble never occurs, since the stationary carrying cable has no
tendency to leave the saddle in which it is carried. This being the
case, there is no difficulty in moving the cars of these lines at a speed
of three or four miles an hour.
3d. — One of the chief advantages of the Bleichert tramways over
all others consists in their capability of surmounting any grade.
In the Hodgson system of single moving-rope tramways, no
grades in the rope are permissible steeper than i in 3)^. In fact, i
in 4 is really about the limit. On steeper grades there is great danger
of the load slipping on the rope. To obviate this danger the Hallidie
system employs a clip which fastens the bucket permanently to the
rope. While this corrects the danger of slipping, it gives rise to the
further and still greater objection that the buckets must be both
loaded and unloaded while moving, since they cannot be stopped
without stopping the whole line.
In the Bleichert system both these objections are i)erfc{'tly ob-
viated.
WIRE ROPE TRAMWAYS. 5
Any grade can easily be surmounted, provided the contour of
the ground is such that the inclination of the carrying cables is not
steeper than i in i. The inclination of these cables does not neces-
sarily follow the contour of the ground in all cases. For instance, in
crossing valleys and streams the Bleichert system permits the use of
long single spans which, in the case of the single moving-rope tram-
ways, would be impracticable. Again, a precipitous rise in the ground
presents no insuperable difficulties, since the curves can usually be
laid out so as to bring the inclination of the carrying cables within
the proper limits. These points are well illustrated in the profiles of
the Bleichert lines built by us for the Granite Mountain Mining Co.,
at Rumsey, Montana, and for the Bi-Metallic Mining Co., at Granite,
Montana, cuts of which are shown on the accompanying chart-sheet.
The second objection is obviated by the arrangement that when
the car reaches either terminal, or any switch or turnout on the line,
it can be automatically disconnected and run off to any point required
for loading and discharging. The Bleichert patent system is also the
only one which permits the introduction at any point on the line of
movable or temporary switches or terminals, without the erection of
special structures for their support.
4th. — The cost of both construction and maintenance is greatly
increased for " single moving-rope tramways " by the use of spans
longer than loo feet, or the occurrence of very steep grades. Even
if only one such span, or one such grade is present in a whole line, it
becomes necessary to make the entire double length of moving
rope strong enough for the special strain due to that one spot, over
which in its endless travel every part of the rope must pass; and this
necessary increase in the size of the rope affects the dimensions of
the supports, sheaves and other fixtures throughout the line, thus
requiring a general increase of cost, nearly as great as if all the spans
were equally long or all the grades ec^ually heavy. The wear of the
rope is also increased by reason of its greater diameter and the more
unfavorable conditions of the catenary curve, or ** sag," on long spans
and steep grades, and these sources of increased cost of maintenance
affect every part of the rope.
Now, in the Bleichert system of tramways, the carrying cable,
being stationary, can be locally graduated to the strains it has to bear.
b ^^BB BOPE TBAMWAYS.
The cable for the empty cars does not, of course, require to be as
strong as the cable for the loaded cars, and it is therefore made only
strong enou^ for the work it has to perform. In like manner, if one
■^or more long spans occur in the line, it is not necessary that the
whole cable should be made strong enough to bear the extra strain
at this one point ; on the contrary, it is sufficient to so strengthen
only the portions exposed to this extra strain. By means of our
patent couplings this is easily practicable. On very long steep grades
also, where the cable at the head of the incline must be able to bear
not only the ordinary working strain due to the cars, but must also
sustain the whole weight of the cable on the incline, this is effected,
in the Bleichert system, by making the cable in sections of gradually
diminishing area, and put together with our patent couplings. In
this way great economy in the total weight of the cables is effected.
A further advantage is, that the traction rope used, instead of being
loaded down by the cars, as in other systems, is itself carried and
supported by them, thus lessening greatly the wear on this rope.
The ordinary spans we use in the construction of these lines are
from 150 to 200 feet, but there is no real objection to spans of 500
to 600 feet. Many lines built within the last few years have spans
up to 1560 feet. The accompanying view (on opposite page), taken
from a photograph, represents one of these, long spans. It is 1,000
feet in the clear, and forms part of a line nearly seven miles in length,
built for the transportation of 250 tons of iron ore per day. This
line has been in successful operation for many years.
As a result of all the improvements made during the last ten
years' practice, in the details of the Bleichert tramways, the wear and
tear and expense of operating our system of lines has been reduced
to a minimum, and we are able to compete niost favorably even with
well equipped surface railroads, in the cost of transportation.
There exists in nature hardly a supposable difficulty or obstacle
which would bar the introduction of this system of transportation;
in fact, in many cases, it is the only one that can be used. While
this is eminently true where the contour of the ground is much bro-
ken up and long spans afre necessary, the Bleichert system possesses
economical advantages even where there are few or no natural ob-
stacles to the building of any kind of road. The service is regular;
WIEE je&PE TRAMWAYS. 7
Stoppages for repairs are rare; no interruptions due either to atmos-
pheric influences or storms are liable to occur; the line being ele-
vated, the service is entirely free from interference with surface
traffic; wear and tear and expense of operating are relatively very
low; terminals can be so arranged that the material transported can
be delivered at the exact spot where it is needed, thus saving all ex-
pense of re-handling. This could not be done with a surface road,
since, even if the cars could be brought close to the point at which
the material is required, there would still be a further expense for
unloading, irrespective of the cost of switching and hauling them.
These facts prove the advantages of a wire rope tramway of the
Bleichert system over short railroad communication^ even under the
simplest conditions and where the surface of the ground would offer
no difficulties to the construction of the latter.
These lines are constructed in a very substantial manner, with
two carrying cables of our special manufacture and anendless traction
rope. The cars are fitted with our patent grips, of which we manu-
facture two kinds — friction and lug grips. Where the grades are
moderate the former are employed; in case they are steeper than i
in 3, the latter are used.
In some cases, where the spans are moderate and the loads to
be carried are light, our " special steel " rods may be substituted for
the carrying cables. These are joined together with our patent
couplings. The cars are hauled by a light, endless traction rope, and
fitted with patent friction or lug grips, as the grades may require.
Such a line calls for the use of numerous couplings, however, as the
steel rods cannot be furnished in lengths of over 50 feet, and its cost
does not differ materially from that of a line equipped with the ordi-
nary carrying cables.
For short lines, where the service is light, the single carrying
cables may be used, instead of the usual two. In such cases con-
venient turnouts are arranged along the line, and the trains of cars
are spaced equally along the endless traction rope in such a manner
that they pass one another at the turnouts. The only advantage
possessed by these single track lines is, of course, their comparative
cheapness of construction. The cost of operating them is about the
same as that of the double track.
/
8 WIBS BOPE TBAMWATa.
In the construction of these tramways every detail has been
thoroughly worked out and proved by actual practice. The materials
used are of the strongest and best, and the workmanship first-class in
every respect. All parts of the machinery are made to standard
gauges and are interchangeable, so that repairs can be made promptly
and cheaply. Every part of the lines is made as nearly automatic as
can be, and thus very little labor is required in operating them. If
required, the cars may be weighed, and counted automatically, and
can be also raised or lowered at any terminal or station by our auto-
matic hoists, from one level to another, or from one floor to another,
without the necessity of any handling. Thus, for instance, goods of
any description can be brought at one level into a warehouse or fac-
tory, raised or lowered to any other floor, and on arriving on that
floor can be conveyed, by means of our suspended rail system, to any
point desired before unloading from the car. The same system is
most economical for loading vessels from docks or wharves. In a
similar manner our system permits the unloading of our car-bodies
upon specially arranged trucks in such a manner as to form mining
cars, which can then be run into the mine or quarry, loaded at the
face of the working, run out to the terminus of the tramway, and
shipped again without any re-handling of the material.
The enclosed chart-sheet of detailed parts will give a general
idea of a few of the various applications to which this system of
tramways is adapted. All these applications are illustrated by lines
actually constructed and in constant operation.
Preliminary estimates of cost of construction and expense of
operating these lines will be furnished in answer to applications made
out on the blank forms attached hereto. Definite estimates can be
furnished only after an exact profile of the ground has been made.
If preferred, we will undertake to make these surveys and profiles by
our own engineers, who are specially acquainted with the require-
ments of our system. This work will be done at the lowest possible
cost.
10 WIBE ROPE TRAMWAYS.
TESTIMONPALS.
[copy.] Office Bi-Metallic Mining Company,
Clark, Montana, August 12th, 1889.
(Philipsburg p. O.)
E. Gybbon Spilsbury, Esq.,
Managing Director Trenton Iron Co., Trenton, N. J.
Dear Sir: Your letter of July 17th, to President Charles Clark, asking for
an expression of opinion concerning the Bleich^rt Tram system (now in opera-
tion between our mine and mill), has been referred to me for reply.
Our line was erected early in the present year, and put in operation May
8th, under the supervision of your engineer, Mr. R. A. Hewitt, and has been
running steadily ever since, without any mishaps whatever.
Since starting, we have transported about eighty-five tons of ore per day
from the mine, at Granite, to the mill, at Clark, a distance of 9,730 feet, and
have also carried up to the mine the greater portion of the supplies used there,
running tramway about six hours per day, at an average cost of twenty-two
cents per ton. By running tramway for twelve hours per day to its full capacity,
we could carry two hundred and forty tons, with practically the same force as is
now employed, thus reducing the average cost to from ten to twelve cents per
ton.
When the line is carrying its load, it develops sufficient power to run a
gx 15 Blake Crusher, and crushes all ore raised at the mine.
We have given the tramway a fair trial, and so far it has given entire satis-
faction. I can cordially recommend the Bleichert system of tramway, built by
your company, to any one requiring a cheap system for the transportation of
ore. Yours truly,
JAMES B. RISQUE, Sup't.
[copy.] Pottsville Iron and Steel Company,
PoTTSViLLE, Pa., May 25th, 1S89.
The Trenton Iron Company,
Gentlemen : Answering yours 24th inst. The Bleichert Tramway that you
built for us is doing very good and satisfactory work. We are carrying forty
to fifty tons per day of ashes at present, and could carry, say fifty per cent.
more with the same men operating it. We think for situations like our own it
is the best mode of carrying away refuse that we know of. You are at liberty
to make use of our name as reference.
Respectfully,
WM. ATKINS, Treas'r.
WIRE ROPE .TRAMWAYS. 11
\
[copy.] Edgewater Lime Works,
Edgewater, N. J., Sept. loth, i88g.
Trenton Iron Company, Trenton, N. J.
Oentlemen : The Bleichert Tramway has been in operation here about ten
months, and has proved itself to be an admirable system for the work we have
to do, which is to carry loose slaked lime from the yard down to the barges at
the dock. I know of no other system which would do this so well under the
circumstances found here.
Yours very truly,
CHAS. F. McKENNA.
[copy.] The Laurentide Pulp Company (Limited),
Montreal, Canada, Nov. 27th, 1889.
Messrs. Trenton Iron Company, Trenton, N. J,
Gentlemen : With your tramway we are now handling fifty tons of pulp
every ten hours. The tramway runs at the rate of two hundred and fifty feet
per minute only, and our experience so far shows that we could easily handle
several times more pulp than this at same speed, without the slightest diflSculty.
We feel sure, also, that the latter result would not be anywhere near the
maximum capacity of the line, but we only speak from actual experience.
When we consider that this tramway takes our product from our wet presses
in the mill, carries it across the three channels and intervening islands of the river
St. Maurice, the third largest river in Canada, and delivers it 1,500 feet away
on the level of our railway siding, and that we do this with three to five horse-
power, and the labor of only one additional man, at the very most, we are more
than satisfied. If there is any other information you require, we shall be glad
to give it. Meantime, we remain.
Yours respectfully,
THE LAURENTIDE PULP CO. (Limited).
John Forman, Sec'y.
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Single Moving-Rope Tramways.
While advocating the use of the Bleichert system for efficient
and economical transportation in general, and especially where it is
necessary to overcome steep grades and long spans and to carry
heavy loads, yet there are many cases where, the grades and the
spans being moderate and the service light, the single moving-rope
system can be used to advantage.
In this System transportation is effected by an endless moving
rope, supported at intervals by pulleys carried by posts or bents.
The loads rest upon and travel with the rope, the loaded carriages
by this method being conveyed to the desired point by one side of
PWTE I.—Box-Head Carriage for Single Moving-Rope Tramways.
the moving rope, while the empty carriers are returned by the oppo-
site side. The rope at the terminals passes around large wheels or
sheaves, power being applied at one terminus sufficient to drive the
rope at a speed of about five miles an hour.
The material to be transported is carried in buckets suspended
from the ropebyanelbow-bent hanger or goose-neck, which brings the
center of gravity of the load directly under the rope, while the shape
of the hanger enables it to pass the supports. The end of the hanger la
fitted into what is known as the box-head (Plate I). This consists of
14 SINGLE MOVING-ROPE TRAMWAYS.
two malleable iron pieces of similar form bolted together. At each
end there are inserted two pieces of rubber, termed " bearing blocks."
The latter, resting upon the rope, are depended upon to prevent the
slipping of the loads in ascending grades or passing pulleys. The
flared ends or wings at the extremities of the box-head are for the pur-
pose of enabling the box- head to pass the carrying wheels. These
wheels are made of various sizes. The depth of the groove is de-
pendent upon the size of rope employed, being so proportioned as to
cause the least possible obstruction to the box-head in passing over
the' wheel. The posts supporting the wheels are ordinarily made of
timber, and, in that case, consist of four uprights, slightly tapered on
all sides and stiffened with latticing. Iron, however, may be used
with advantage under certain circumstances and in certain localities.
These supports are ordinarily placed about loo feet apart, although
spans as great as 300 feet have been employed.
The buckets or boxes for coal, clay or minerals, are made cylin-
drical in outline, and may be proportioned to carry from 50 to 150
pounds of material (Plate II,, Fig. i). The bucket is attached to the
hanger by means of a stirrup rod, pivoted to the bucket. In order
to facilitate the dumping, the pivot centers are placed slightly below
the center of gravity of the bucket. In some instances the buckets
are fitted with wheels, to admit of their being moved along the ways
of a mine, quarry or clay pit (Plate II., Fig. 2). For the transporta-
tion of special goods, other forms of carriers are adopted.
By reference to Plate I. it will be noticed that the box- head is pro-
vided with two grooved wheels. The purpose of these wheels is to lift
the box-head and bucket free of the rope when it becomes necessary
to load or unload. This operation is performed by having at the ter-
minal stations a fixed rail, so placed as to receive the small grooved
wheels as they reach the terminal points This arrangement is shown
in Plate II., Fig. 3. It is evident that the box-head, in order to be free
of the rope, must either run up an inclined terminal rail or must be
deposited on the rail by depressing the rope at the point where it
meets the terminal rail. The former is the preferable plan and the
one generally adopted. The buckets are thus, in either case, sus-
pended from a fixed rail, which may be laid to convenient points of
loading or unloading, while the motion of the rope continues unin-
SINOLE UOnNQ-ROFE TKAVWATS.
Plate II. — Details; Single Moving-Rope System.
16 SINGLE MOVING-BOPE TRAMWAYS.
terrupted. Since the level of the rope varies with its tension and the
weight of the buckets, it is necessary to locate carrying wheels at the
extremities of the rails.
The rope at the power terminus passes round a driving sheave
(Plate II., Fig. 3). For lines exceeding half a mile in length vertical
drivers are preferable, the particular details being suited to the
requirements of the lines.
In order to enable the rope to accommodate itself to a variable
tractive force, it is necessary to adopt some expedient for compen-
sating this variation. The most efficient arrangement is that of
locating the driving and tightening drums at the same terminal, be-
cause the slack rope paying off the driving sheave can then be taken
up with ease, since the tension on the rope is least on the outgoing
and greatest on the incoming side. The tightening drum is, ordi-
narily, merely a sheave resting upon a carriage. The axle of the
sheave has attached at each side the ends of U-shaped strap, con-
structed so as to clear the rim of the sheave. The strap is fitted with
a hook to take the end of a chain which, passing over a wheel into a
pit, is attached to a heavy weight.
The original method of passing curves of slight change in direc-
tion was to set the carrying or bearing wheels at a slight angle to the
vertical, so as to throw the upper part of the rims outward. It was
found, however, that very little irregularity in action would cause the
rope to leave the groove of the wheels, and for this reason the method
has had a very limited application.
■ For curves of larger angle, according to one system, horizontal
wheels are introduced, the load upon reaching the curve being thrown
upon a switch rail similar to that described for the terminus. These
horizontal wheels are secured to a frame in such a manner that each
divides about 10*^ of the total curve; they are the same as the ordi-
nary carrying wheels, but in this construction are set horizontally.
The arrangement for the outer curve is comparatively simple, as
the hanger passes around outside the rope, while the curve wheels
are inside. For this reason it is only necessary to bend the switch
rail around the outside of the wheels. With the inside curve the
horizontal wheels come between the rope and the hanger bar; con-
sequently, the rail has to be curved so as to clear the box-head away
SINGLE MOVING-ROPE TBAMWAYS. 17
from the rope and bHng it out behind the rim of the wheels, down
again to the rope.
In order that the action of the box-head, in following the switch
rail on a curve, may be automatic, it is necessary that the rail should
have a fall of not less than i in 15. To obtain this slope the out-
going side of the rope must be depressed sufficiently to furnish the
necessary fall to the switch rail. For this purpose a depressing wheel
is placed over the rope near the last horizontal curve wheel. The
action of the curve is then as follows; the box-head and bucket ad-
vance with the rope, the little side wheels run on the rail and along it
down the incline on the rope again.
This depressing wheel has proved itself in many cases to be
highly detrimental to the accurate working of curves; aside from this
the operation of the above curve expedient has not proved itself en-
tirely satisfactory. For this reason The Trenton Iron Company have
adopted several new curve devices, suitable to various requirements.
Their action is positive and automatic, and their introduction greatly
simplifies the problem of curvature.
In locations where the line of tramway crosses a valley and the
change from descent to ascent is sudden, it has been found necessary
to introduce what is termed a " holding down " apparatus. The de-
vice usually applied is simple and inexpensive in construction.
Now, a few words as to the general action of the plant when in
operation. The power sheave being started, the line of rope begins
to move almost simultaneously along its entire length; the box-heads,
with loaded buckets attached, are allowed to drop upon the rope and
are carried to the discharge terminal, when the box-head wheels are run
upon the terminal rail and the bucket is carried automatically down
to the unloading point. Angles either slight or sharp are passed and
inclines as heavy as i in 4 ascended. After unloading, the box-head
and empty bucket are run upon the opposite side of the rope and
returned to the loading point.
The question is often asked as to what would be the result if the
rope should happen to break. The view is sometimes advanced that,
in such an event, all the boxes on the line would fall to the ground,
but this is evidently not the case. One or two spans only, located
near the point of break, would be affected to such an extent, while
18
SINOLB HOYINGHBOPE TBAMWAT8.
for the remainder of the line a gradually diminishing effect would be
produced, until the degree of slackness would become imperceptible.
Preliminary estimates of cost of construction and expense of
operating these lines will be furnished in response to applications
made out on the blank forms attached hereto. Definite estimates can
be furnished only after an exact profile of the ground has been made.
If preferred, we will undertake to make these surveys and/ profiles by
our own engineers, who are specially acquainted with the require-
ments of the system. This work will be done at the lowest possible
cost.
The following are some of the single moving-rope tramways con-
structed by us:
LIST OF
SINGLE MOVING-ROPE TRAMWAYS
BUILT BY THE AUTHOR.
FOR WHOM.
LOCALITY.
Material
Transported.
.-I « g I
as P«^
03*5
G. H. Nichols & Co iCapelton, Can.
J.P.Clark (Shooter's Hill,
-' ( Jamaica,
Reading Iron Co
Reading Iron Co
Juniata Sand Co. .
Reading, Pa. . .
(
!
Wrought
iron pipe
Coal
Lewiston. Pa. . iSand.
150
«
o »
P aj
'^ e
Copper pyrites 100 ! 4,475
1
Bananas.... 30 114,125
J i
y 100 I 1,320
660
7,920
Quarry Cable Hoists.
In quarrying, rock cutting, dam building, and many other
operations where it is necessary to hoist and convey large individual
loads economically, it frequently happens that the use of the derrick
system, by reason of the limited area of its efficiency, is imprac-
ticable.
To meet such conditions our Quarry Cable Hoist system is ad-
mirably adapted, for it can be efficiently operated in spans up to
I, GOO feet, and in lifting individual loads up to fifteen tons.
These hoists are divided into two classes; the " endless rope "
and the "inclined." In both of them a carriage, with a block
attached, travels upon a suspended cable, which, after passing over a
tower or towers, is firmly anchored in the ground at each end. These
cables are fitted with turnbuckles to give them the requisite tension,
and where they pass over towers are provided, if necessary, with
saddles of special design, containing rollers which lessen the strain
on the towers and also the wear on the cable.
By means of an endless traction rope, attached to the carriage
and wound on a drum, the carriage can be moved forward and back-
ward upon the carrying cable and stopped at any given point.
A hoisting rope, supported by trolleys, is connected with the
block, and lifts the load, which can then be conveyed to, and lowered
from any point on the line.
Both the traction and the hoisting ropes are operated by an en-
gine specially designed for the purpose, which may be located at
either end of the line.
The construction of the " endless rope " hoist is clearly shown
by the cut on opposite page.
When the difference in elevation of the terminals is considerable,
one of the towers may usually be dispensed with, the carrying cable
being anchored directly in the ground. In such cases, where the
cable is inclined sufficiently to permit the carriage to run down by
22 TRANSMISSION OF POWEB.
To illustrate: Let us suppose a bar of iron, having a cross-sec-
tional area of one square inch, to move end-long at a rate of two feet
l)er second. If the resistance overcome is, say, 5,000 pounds, work
will be performed at the rate of 10,000 foot-pounds per second.
But, if we double the velocity of the bar, we shall transmit twice the
amount of work with tbe same strain, or the same work may be
produced with only half the former strain; i. e., by a bar having an
area of only half a square inch. In a similar manner, if we move
the bar with the velocity employed in wire rope transmission, viz.,
about eighty feet per second, then, while doing the same amount of
work, the strain on the bar will be reduced from 5,000 to 125 pounds,
and the bar will need a section of only ^ square inch. To use an
extreme illustration, we might conceive of a speed at which an iron
wire, as fine as a spider's web, would be able to transmit the same
amount of work as the original one-inch bar.
By the aj^plication of these simple principles the greater part of
the force is first converted into velocity, and at the place where the
power is required the velocity is changed back into force.
The Rope.
The section of wire rope best suited, under ordinary conditions,
for the transmission of power is composed of six strands of seven
wires each, laid together about a hempen center. Ropes of twelve
and nineteen wires to the strand are also used. They are much more
flexible, and may be ai)plicd with advantage under conditions which
do not allow the use of large transmission wheels, but admit of high
speed. They are not as well adapted to stand surface wear, however,
on account of the smaller si/e of the wires.
1^0 th iron and steel wire rt)pes are employed for the transmission
of ])ower, but iron is to be preferred, as it is better adapted to with-
stanil the rapid bending antl vibration to which the rope is subject;
but si)e( ial (\ire is ncressary in the selection of the material, and only
the touufhest and best u^rades of iron should be used. Our extensive
experience in the manufacture of wire, covering a period of over
ihirlv vears, is a sufliciont guarantee of the excellence of the material
used in our rones.
TRANSMISSION OF POWER.
23
The Driving Wheels.
The driving wheels (see Figs, i and 2) are usually of cast iron,
and are made as light as possible consistent with the requisite strength.
Wheels with wrought iron- spokes have been used, but the increased
cost of these renders their application limited to exceptional cases,
where it is important to have wheels as light as possible. Various
materials have been used for the filling, such as tarred oakum, jute
yarn, hard wood, India rubber and leather. The filling which gives
the best satisfaction, however, for transmission purposes, consists of
Fig. I.
Fig. 2.
segments of leather and blocks of India rubber, soaked in tar and
packed alternately in the groove, and then turned out to a true sur-
face. Where the rope is subject to considerable lateral vibration, the
flanges are sometimes lined with sole leather by riveting; but such
cases are rare.
Intermediate Supports.
In long spans, intermediate supporting wheels (see Figs. 3 and 4)
are frecpiently used, and it is usually sufficient to support only the
slack or following side of the rope; but whatever the distance that
the })Ower is transmitted, the driving side of the rope will require a
u
TBUIBU1B8I014 OF POWEB.
less number of supports than the slack side. The sheaves support-
ing the driving side, however, should in all cases be of equal diameter
with the driving wheels; for it makes no difference whether the rope
laps half way round or only ipmrter way round these sheaves, the
tension induced by bending is the same. With the slack side, how-
ever, smaller wheels may be used, owing to the fact that there is less
tension on this side, and the rope is therefore better able to stand the
additional tension due to the bending; but the diameter of the sup-
porting sheaves in this case should not be less than one-half that of
the driving sheaves.
FiR. 3.
FiK- 4-
The system of carrying sheaves may generally be replaced to
advantage by that of intermediate stations. The rope thus, instead
of running the whole length of the transmission, runs only from one
station to the other; and it is advisable to make the stations equi-
distant, so that a ro])e may be kept on hand, ready spliced, to put on
the wheels of any span, should its rope give out. This method is
greatly to be preferred where there is sometimes a jerking motion to
the rope, :is it prevents sudden movements of this kind from being
transmitted over the entire line.
TRANSMISSION OF POWER. 25
MATHEMATICAL PRINCIPLES INVOLVED.
Nomenclature.
D = diameter of rope, in inches.
d = diameter of individual wires.
£ = modulus of elasticity = for iron 28,500,000.
J^ =z resistance due to journal friction.
g = force of gravity in feet per second = 32.19.
A = deflection of rope at center, when at rest, in feet.
^, = deflection of driving side of rope at center, in feet.
//g = deflection of following side of rope at center, in feet.
IT = force transmitted.
A'l — force transmitted after allowing for centrifugal force.
k ■— safe stress per scjuare inch on wires = for iron 25,700 lbs.
.k^ = stress per square inch due to S^ = k — kc^,
k^ = stress per sq. in. due to bending of wires around sheaves
JV = actual horse-power transmitted.
JVq = gross horse-power transmitted.
JV^ = loss of horse-power due to centrifugal force.
iV3= loss of horse-power due to journal friction.
n = number of wires in rope.
P z= force necessary to overcome journal friction,
Q = applied weight or pressure on wheels.
^ = weight of rope per foot =1.5 Z>^.
R = radius of wheels in inches, assuming ])oth of same size
r = radius of shaft or axle.
*$" = Span between axes of wheels, in feet.
s = tension of rope at rest.
S'l = tension of driving side of rope.
S2 = tension of following side of rope.
y = number of revolutions of wheels per minute.
V = velocity of rope in feet per second.
JV = total weight of rope.
w = weight of wheel and axle.
X = ratio of radius of wheel to diameter of rope.
jp = coefficient of journal friction = .08.
^
\
26 TRAlfSMISSION OF POWER.
Tension of the Rope.
Referring to Weisbach, we have,
s^ = 2A = -^--% (i)
S^ = X — , . . o . (^2)
_ 825 ATq f .
we also have
7r^2
«
•^1 =
^u - • '- (4)
4
hence
^0 = —TTZT- = .0003702 I?^vki ; • • • • (5)
4400
but
^t = ^ — ^2y c - . . (6)
and referring again to Weisbach, we find,
^. -^-
For rope best suited for the transmission of power, we have,
hence
^^=78^ ^7)
Combining the above equations, 5, 6 and 7, we have,
££>
JVq = .0003702 I?hf (k — ^^), (8)
the ordinary formula for determining the total gross horse-power
developed.
In order to arrive at the actual horse-power transmitted it will
be necessary to determine the losses due to centrifugal force and
journal friction.
TRANSMISSION OF POWBR. 27
The loss due to the resistance of the air is so slight that it may
be neglected.
Loss Due to Centrifugal Force.
Referring once more to Weisbach, we find for the measure of
centrifugal force,
hence
S, = 2K,+^ (9)
o
in which K^ represents the force transmitted, after allowing for the
influence of centrifugal force.
But
and
^i — y > (10)
^ _ HOC iVp
^ V
<*
from which, after substituting in equation 9 and transposing, we
find that the loss due to centrifugal force is
iVj = .0000424 D^ v^ (11)
Loss Due to Journal Friction.
Loss of power from this cause varies directly as the pressure of
the journals on the bearings, due to the tensions of the driving
and following sides of the rope, and to the weight of the wheels and
axles; that is,
PR = Fr;
but F = {s^ -^ S2-\- w) if — (zK 4- w) %
15150 iVn . . X
and K =- " (see equation 2),
V
N
(1650 --+ w) H>r
7.'
hence P — —5 •
K
28
TBANSHIS8ION OF POWEB.
Assuming <p = .08 and —^ = .03,
P = (1650 — - -\- w) .0024, (12)
and we have for the amount of horse-power absorbed
N^ = — = .0000045 (1650 A^Q + 7£fv). (13)
The foregoing determination applies only to the driving and
driven wheels. At an intermediate station the friction is due prin-
cipally to the vertical pressure of the weight of the wheels, axles and
rope between the two stations, on account of the neutralization of
the nearly horizontal tensions. The loss in terms of horse-powers,
due to this cause, is expressed by
.0000045 0^"^ + ^^0 ^'•
To find the pressure on the bearings at any intermediate station,
the simplest method is by construction (Figs. 5 and 6). Make AB —
TRANSMISSION OF POWEB. 29
and parallel to T; BC = and parallel to T^ ; CD = and parallel to
t; Z>u£'=and parallel to t^; and -fi"/^ vertical and == the weight of the
wheel and axle. Then the line connecting A and F will give the in-
tensity and direction of the resulting pressure.
Actual Horse-Power Transmitted.
Combining the equations 8, ii and 13, we obtain for the actual
horse- power transmitted
N=Nq — iVi — N^—D^ V [.0003675 (>& r-^) — .0004242/] — .0000045 wz/. ...(14)
^ I oil'
It is evident from the above formula that a certain ratio must
exist between D and R which will give a maximum value to N.
Let us suppose
R
D -
X
and for convenience
a = .0003675,
b = .0000424,
c = .0000045.
The above formula then becomes, approximately,
JV ^ aR^^i^ - —-)-,^; (15)
It is evident that the value of JV will be a maximum when the
expression in the parenthesis becomes a maximum. Differentiating
this expression, therefore, and placing the first differential coefficient
equal to o, we obtain
du 54^ 2/' _ K 2k , .
dx 324A:* x^ 6.V* x^
hence
^ ^ i^"'-^^*^'^* ^^^^
or, the diameter of the wheels should be, approximately, 185 times the
diameter of the roi)e. In other words, the ratio between the diameters
of the wheels and rope should be about a foot to a sixteejith of an inch.
30 TRANSMISSION OF POWER.
Substituting this value of x in equation 15, we find
^ £ __
and N = (jiR^'— cw)v..... (18)
Assuming an average value for w of yV -^^> which is allowable,
since the influence of w is trifling in any case, we have
N = .0003648^^27;^ (1^)
or, substituting the value of -^ = 92.413/^,
iV^=3.ii54Z>2z^, (20)
but V = -^ /^F= .So6sZ>K (21)
hence iV = 3.0148 I?^V. (22)
That is, f/ie actual horse-power transmitted approximately equals three
times the cube of the diameter of the rope^ expressed in inches^ multiplied
by the number of revolutions of the wheels per minute. This rule, of
course, is based on the assumption that the diameters of the wheels
are equal, and about 192 times, or not less than 185 times the
diameter of the rope.
Deflection of the Rope.
It is evident that the tensions on the rope depend upon the de-
flections, consequently it is necessary to determine the latter before
we can give the rope the above calculated tensions. The formulae
for determining these deflections are as follows (Weisbach, vol. iii.,
pages 240 and 241):
*.=f=s ■ t'^)
*-=C=^i' <-)
and h = - =f-^-, (25)
but (/
\.SD^ and A'=^^^
to
to to •
to
•> * to
TRANSMISSION OF POWER. 31
By substituting these values in equations 23, 24 and 25, we
would obtain expressions for the deflections in terms of A"q, but by
combining equations 8 and 21, we find
^0 = 3.1791^'^, (26)
hence K = 2i68Z>«, (27)
and //j = .00004326" ^ (28)
/12 = .oooo864»S'^, . . (29)
h = .00005 765 6" ^ (30)
From the foregoing formulae we deduce the following
TABLE OF HORSE-POWERS.
F= 75 100 125 150 175 200 225 250
4 i 351 469 5'^^ 703 8.20 9.37 10.55 11-72
5 1^ 6.87 9.16 11.44 13-73 16.02 18.31 20.60 22.89
6 I 11.86 15.82 19.77 23.73 27.69 31.64 35.60 39.55
7 yV 18-84 25.12 31.40 37-68 43-96 5024 5652 62.80
8 ^ 28.12 3750 46.87 56. 25 65.62 75.00 84.37
9 t\ 40 04 53-39 66.74 80.09 93-44 106.79
10 J 54-93 73-24 91-55 109.86 128.18
11 H 73-11 9748 121.85 146-23
12 |- 94-92 126.57 158.20
The proper deflections corresponding to the. above, when the
rope is at rest, are as follows:
Span, in feet . 50 100 150 200 250 300 350 400 450
Deflection.... if 7^ i'3r 2' 3r 3' 7^ 5' 2^ 7'r 9' 2^' n'S^
Limits of Span.
It becomes interesting to ascertain between what limits of span
the transmission of power by wire ropes is i)racticable. When the
deflections are very small, it is impossible to splice the rope to such
a degree of nicety as to obtain exactly the required deflection, and it
becomes necessary to apply means for giving the proi)er tension to
32 TRANSMISSION OF POWER.
'the rope. The rope is also subject to a certain amount of stretch,
and tightening sheaves are reported to in order to avoid frequent
splices, which are objectionable; but care should always be exercised,
in using tightening sheaves, that they do not become the means, in
unskilled hands, of overstraining the rope. When it is inconven-
ient to apply tightening sheaves, the wheels may be re-filled with
a thicker filling, or a temporary lining of wooden blocks put in, by
nailing to the filling already in the wheels, and the rope run on these
until it has stretched to a constant length, when this lining is removed,
the rope re-spliced, and placed again on the original filling. On the
shorter spans, moreover, the rope is more sensitive to every irregularity
in the wheels and amount of power transmitted, and it is apt to sway
to such an extent beyond the narrow limits of the required deflec-
tions as to cause a jerking motion, which is very injurious to the rope.
It has been found in practice that when the deflection of the rope at
rest is less than three inches the transmission cannot be effected with
satisfaction, and that shafting or belting is to be preferred. This
deflection corresponds to a span of about 54 feet.
In regard to the maximum limit of span, the available height of
the towers or supports for the wheels must be taken into considera-
tion. It is for this reason that it is customary to make the under
side of the rope the driving side, as in this case the greater deflection
in this side occurs when the rope is at rest. When in motion the
under side rises and the upper side sinks, thus enabling obstructions
to be avoided which otherwise would have to be removed, or necessi-
tate very high towers. The maximum limit of span, therefore, is
determined by the maximum deflection that may be given to the
upper side of the rope when in motion. Assuming that the clearance
between the upper and lower sides of the rope should not be less than
two feet, and that the wheels are at least ten feet in diameter, we have
h^ + 10 = >^2 + 2,
and since h^ = 2^^,
we have ^^ = 8 feet.
This deflection corresponds to a span of about 430 feet.
transmission of power. 33
Inclined Transmissions.
It generally happens that the two wheels are not on the same
horizontal plane, but that one occupies a higher elevation than the
other. There will be a difference in the tensions in this case at the
two wheels, the upper one being subject to a greater tension, but this
difference is so slight, for all practicable spans, that it may be neg-
lected as far as it affects the amount of horse-power that may be
transmitted. It is evident, however, that when the angle of inclina-
tion is very great, the proper deflections cannot be readily determ-
ined, and the rope becomes more sensitive to the ordinary varia-
tions in the deflections, so that tightenihg sheaves must be resorted
to for producing the requisite tension, as in the case of very short
spans. In other words, the span to be considered in such cases is
really the horizontal distance between the two wheels, and practice
has shown that when this is less than sixty feet, or when the angle
of inclination exceeds thirty to forty-five degrees, it will be found
desirable to use tightening sheaves. The limi|:ing case of inclined
transmissions occurs when one wheel is directly above the other.
The rope in this case produces no tension whatever on the lower
wheel, while the upper is subject only to the weight of the rope,
which is usually so insignificant that it might be neglected altogether
without materially affecting the problem, and tightening sheaves are
therefore an absolute necessity. If the rope and wheels are propor-
tioned according to the preceding rules for maximum efficiency, the
proper load for the lower wheel is given by the equation,
S^ = 2A' = Q -f- 7£' = 4336/^^ (see equation 27). . .(31)
Variations in Size of Wheels.
The foregoing formulae and table of horse-powers have been
estimated on a basis of maximum efficiency upon the assumption that
the diameters of the wheels are not less than 185 times the diameter
of the rope. It frequently happens, however, that it is impracticable
to use wheels of such large diameter, and smaller ones may be used;
but of course it will be understood that the efficiency of the trans-
mission is lessened and the wear on the rope correspondingly in-
creased.
34 TUANSMISSION OF POWER.
Referring to equation 7, we find
ED . D
^'8 = -—^W = 1583333
18^ J 0000 j^ ,
from which, substituting some of the most probable values of — ^,
we deduce the following table:
R
D
K^
R
D
k^
19.2
82463
60.
26388
24.
65971
64.
24739
28.8
54975
67.2
23561
32.
49478
72.
21990
36.
43980
76.8
20616
38.4
41232
80.
19791
40.
39582
84.
18849
48.
32986
86.4
18326
56.
28273
Z%,
17992
57.6
27488
96.
16493
This table is interesting, as it clearly indicates the cause of the
rapid wear of the ropes when running on small wheels. When the
ratio -^ is large, the tension varies but slightly, with small
changes in this ratio; while, if the ratio is small, the tension increases
at a much faster rate than -^ decreases.
Hitherto we have assumed that the two wheels are of equal size,
and it is always desirable to have them so if possible, but it is fre-
quently convenient to make them of different sizes in order to ob-
tain the requisite speed in the driven mechanism. In this case the
power transmitted will be the same as if the two wheels were of the
same size and equal to that of the smaller wheel, running with a
speed corresponding to the speed of this wheel.
TRANSMISSION OF POWEB. 35
Equivalent Belt.
Weisbach gives
■N = -^
II oo
as the value of the number of horse-powers which may be transmit-
ted by a belt of the breadth b in inches, and of the velocity v in feet
per minute. When it is desired to transmit by means of a wire rope
the entire power of a belt, the above formula will be found con-
venient.
Concluding Remarks.
Transmission wheels should be nicely balanced; otherwise un-
even wearing will result in the bearings, as also in the filling, causing
the rope to sway violently. If the splice is poorly made, the filling
roughly inserted, or the wheels not keyed at right angles to the shaft,
similar irregularities in motion will result.
It must be borne in mind that no pains should be spared at the
outset to the careful alignment and equal balance of the wheels, on
account of the high velocities at which they are run.
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